The present invention relates to a multi-pole high speed generator, and, more particularly, to a rectifier module assembly that mounts within a multi-pole high speed generator. The rectifier module has a circuit with improved reliability that rectifies a multi-phase AC signal generated in the exciter armature windings of the multi-pole high speed generator, and provides the rectified DC signal to the field winding of the generator.
Generators that are installed in aircraft typically rotate at relatively high speeds (e.g., 24,000 r.p.m. or greater), and are also typically of the so-called xe2x80x9cbrushlessxe2x80x9d generator design. Generally, brushless generators include three distinct generating systems, a permanent magnet generator (PMG), an exciter, and a main generator. The PMG may include a plurality of permanent magnets that rotate with the generator rotor, and which induce a current into a set of windings. This current is typically fed to a regulator or a control device, which in turn outputs a DC signal.
The exciter may include a plurality of stationary field windings, which are electrically coupled to receive the DC signal output from the regulator or control device, and thus develop a magnetic field. The exciter may also include armature windings mounted on the generator rotor, which rotate within this magnetic field. Thus, during rotation an AC current is induced in the exciter armature windings. Typically, the exciter armature windings are wound such that the induced AC current signal is a three-phase AC current signal. Rectifier circuits that rotate with the exciter armature windings rectify the three-phase AC current signal induced in the exciter armature windings. The DC current output from the rectifiers is provided to the main generator.
The main generator includes rotating field windings and stationary armature windings. The rotating field windings are electrically coupled to receive the DC current from the rectifiers and develop a magnetic field that rotates with the rotor. This rotating magnetic field induces a three-phase AC current in the stationary armature windings. This three-phase AC current is then provided to a load.
As noted above, the generators installed in aircraft typically rotate at relatively high speed. Thus, the rectifiers that rotate with the exciter armature, colloquially referred to as xe2x80x9crotating rectifiers,xe2x80x9d are subjected to relatively high centrifugal loads. One conventional rotating rectifier assembly is arranged radially along a surface or a base within the generator, and thus experiences varying centrifugal loads across its components. Alternatively, another known rotating rectifier assembly is permanently mounted within a rotating housing and thus does not allow easy maintenance and/or replacement.
In addition to the above-noted structural weaknesses, conventional three-phase rotating rectifier circuits include only a single resistor to provide protection for the rectifier diodes. This single resistor is generally a wire-wound resistor, which is itself subject to failure modes resulting from the centrifugal loads it experiences during rotation. Moreover, the electrical failure of this single resistor results in the rectifier circuit being unprotected from voltage and/or current spikes that may occur within the generator.
Hence, there is a need for a multi-pole high speed generator having a rectifier circuit that improves upon the drawbacks identified above. Namely, a rectifier circuit that is less likely to fail from varying radial centrifugal loads and/or that is more reliable, and/or easier to repair and replace.
The present invention provides a multi-pole high speed generator having a rectifier circuit that is less likely to fail from varying radial centrifugal loads, is more reliable, and is easier to repair and replace.
In one aspect of the present invention, a rectifier module assembly includes a substantially flat base that has a plurality of conductive circuit runs formed on it, and which is dimensioned to be mounted within a hub of the exciter. A first diode circuit, which includes an anode and a cathode, has its anode electrically coupled to a first of the plurality of conductive circuit runs. A second diode circuit, which also includes an anode and a cathode, has its cathode electrically coupled to a second of the plurality of conductive circuit runs. A conductive element electrically couples together the cathode of the first diode circuit and the anode of the second diode circuit.
In another aspect of the present invention, a rectifier module assembly includes a substantially flat base that has a plurality of conductive circuit runs formed on it. A first diode circuit, which includes an anode and a cathode, has its anode electrically coupled to a first of the plurality of conductive circuit runs. A second diode circuit, which also includes an anode and a cathode, has its cathode electrically coupled to a second of the plurality of conductive circuit runs. A resistive element is electrically coupled between the first and second conductive circuit runs. And a conductive element electrically couples together the cathode of the first diode circuit and the anode of the second diode circuit.
In yet another aspect of the present invention, a rectifier circuit for rectifying a multi-phase AC signal generated in a plurality of exciter armature windings of a multi-pole high speed generator and providing a DC signal to a field winding of the generator includes a plurality of parallel-connected rectification circuits. Each of the rectfication circuits includes an AC input terminal for receiving one phase of the multi-phase AC signal, and first and second DC output terminals for providing the DC signal to the field winding. Each of the rectification circuits further includes a first diode circuit, a second diode circuit, and a resistive element. The first diode circuit has its anode electrically coupled to the AC input terminal and its cathode electically coupled to the first DC output terminal. The second diode circuit has its cathode electrically coupled to the AC input terminal and its anode electrically coupled to the second DC output terminal. The resistive element is electrically coupled between the first and second DC output terminals.
Other features and advantages of the high speed generator will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.